Carburetor control system and method for regulating air to fuel ratio

ABSTRACT

As a means of providing improved control of the air-fuel ratio to an internal combustion engine for, in turn, maintaining control of the exhaust gas properties there is a regulation of fuel input responsive to a pressure exerted on the fuel in the carburetor float chamber. Sensing means are provided to be responsive to ambient conditions and/or to a given exhaust gas component. Such sensors, along with transmitter means, are integrated into the system to have fuel flow increased or decreased by pressure in the float chamber proportional to the net effect of having an increasing or decreasing quantity of O2 present.

United States Patent 1191 [111 3,7 Gerhold 1451 May 1, 1973 15 CARBURETOR CONTROL SYSTEM 2,248,090 7/1941 Kittler ..123/140.3 AND METHOD FOR REGULATING AIR 2,557,] l 1 6/1951 Jorgensen et a1 ..26l/DIG. 67 2,796,243 6/1957 McDuffie ..26l/DlG. 67 To FUEL RATIO 3,036,564 5/1962 Guiot ....123/14O MC [75] Inventor: Clarence G. Gerhold, Palatine, Ill. 3,533,381 10/1970 Schmid ..l23/1 19 [73] Assignee: g g i Products Company Primary Examiner-Wendell E. Burns es ames Attarney-lames R. Hoatson, Jr. and Philip T. Liggett [22] Filed: May 25, 1970 57 B T C [21] Appl.No.: 40,182 1 A S RA T As a means of providing improved control of the airfuel ratio to an internal combustion engine for, in [52] CL123/ll9 123/140 ZGI/DIG' turn, maintaining control of the exhaust gas properties 261/70 261/72 there is a regulation of fuel input responsive to a pres- [51] Int. Cl. ..F02m 7/00, F02b 33/00 sure exerted on the fuel in the Carburetor float Fleld of Search 67, 70, 'chamber Sensing means are p i to be responsive 261/72; 123/119 140 MC to ambient conditions and/or to a given exhaust gas component. Such sensors, along with transmitter [56] References C'ted means, are integrated into the system to have fuel flow UNITED STATES PATENTS increased or decreased by pressure in the float chamber proportlonal to the net effect of having an ml,999,5l7 4/l935 Prentis ..26l/DIG. 67 creasing or decreasing quantity of 0 present, 2,023,647 12/1935 Schmid ..26l/DlG167 2,244,669 6/1941 Becker 123/140 MC 13 Claims, 4 Drawing Figures 29 Temperature Transmitter -$caler 30 Barometric Pressure Transmitter- Sea/er f A 'k Hum/arty Transmitter-Sealer Regulated Pressure 00 Carburetor Chamber Carburetor F/oat Chamber Computing Relay Patented May 1 1973 3,730,157

2 Sheets-Sheet 1 Figure 4 v REGULATED PRESSURE ON CARBURETOR CHAMBER Can/ro/ Device E rig/he lmake Marl/fold Exhaust Gas Ca/a/yt/c Con verfers 8 a 0 -40m F/gure y 0 Confen/ Transm/lrer-Sea/er 33 23 29 Temperature Transm/Her-Sca/er 30 Barometric Pressure Transmitter-Sealer I 3/ Humid/7y Transm/Her8ca/er 32 EH a 36 Regulated Pressure 38 39 A if 0n Carburetor Chamber Carburetor F/oaf Chamber 22 l r r 2 27 r C r R W e Figure 3* J, /V V E/V 7'0 R:

2/ Clarence G. Gerba/d Patented May 1, 1973 3,730,157

2 Sheets-Shet 2 Conversion vs. Corourelion I00 I I Lorbon Monoxioe'\ ,"'Hyo'rocorbon so g x 0 40 //V/lrous Oxide 30 I l I l /4.50 /4.45 /4.40 7 I435 Air To Fuel Raf/o 0 1 1 I I I 1 l 1 1 "70 Carbon Monoxide, Ho! Cycle Emission Weigh/ed) F g are 2 IN VE/V TOR" G/oren co 6. Gerho/d A TTOR/VEYS CARBURETOR CONTROL SYSTEM AND METHOD FOR REGULATING AIR TO FUEL RATIO The present invention relates to an improved method and means for operating an engine carburetor system so as to provide corrective variations in the air-fuel ratio and thereby obtain a desired exhaust gas composition.

More particularly, the invention is directed to a method and system for regulating the air to fuel ratio by varying pressure in the carburetor float bowl. In other words, fuel flow is increased or decreased to the fuelair mixing section of the carburetor responsive to one or more sensors which will provide signals indicative of an increase or decrease in the amount of oxygen reaching the engine and being carried through the engine to an exhaust gas converter zone.

The change in ambient conditions which will affect the actual amount of present and the air-fuel ratio will include changes in air temperature; barometric pressure and humidity. Thus, to provide a desired steady-state" exhaust gas stream composition for a par ticular mode of engine operation, there are provided sensing means and accompanying amplifying or transmitted means to effect corrective variations in the fuel introduction for changes in any one of these ambient conditions, A correction in the air-fuel ratio for any one ambient change affecting 0 content is of advantage; however, the sensing of all of the changes and the scaling and totalizing thereof is preferable. In addition to, or in lieu of sensing ambient conditions, there may be the analysis of the engine exhaust gas stream to measure 0 or CO content and then providing an adjustment of the air-fuel ratio in accordance with the method of the present invention so as to obtain desired CO and 0 levels in the exhaust gas stream.

BACKGROUND In connection with the problem of reducing air pollution resulting from the automobile internal combustion engine, it has been found that there can be a highly efficient catalytic conversion of noxious components, [i.e., hydrocarbons, carbon monoxide (CO) and nitrogen oxides (NO,)] from the exhaust gases if there is a suitable engine design and a close control of the carburetion or air-fuel introduction. For example, test data indicates that best catalytic conversion results are obtained with the engine operating on the lean side and there being an approximate stoichiometric air to fuel ratio. Actually, the nitrogen oxides conversion by many of the oxidizing catalysts used has been optimum where the exhaust gases have a reducing atmosphere (i.e., high levels of hydrocarbons and CO present); however, on'the other hand, where air-to-fuel ratio is controlled and there is no excess air or fuel, it appears that catalytic conversion becomes optimized and even residual nitrogenoxides fall to a low level.

OBJECTS OF THE INVENTION As an object of the present invention to obtain better catalytic conversion of engine exhaust gases, there is herewith provided a method of more closely controlling the air to fuel ratio, or more particularly fuel input at the carburetor zone, by adjusting the pressure on the fuel in the carburetor chamber responsive to at least one ambient change affecting 0 content.

It may be considered a further object of the present invention to provide a carburetor control system which incorporates the use of one or more sensing means and accompanying transmitting and regulating means such that the fuel to air ratio will be adjusted by varying pressure applied to the fuel in the carburetor chamber. The system may be such that only one sensor-transmitter affects the pressure control to the carburetor bowl. However, in a more elaborate system, a plurality of sensor-transmitters will be connected to a computing or totalizing relay device, which will transmit a net effect to the pressure regulating means.

As a still further object of the invention, it is to be noted that the sensing or signaling means for the system may be from the analysis or measurement of a, particular exhaust gas component, such as O, or CO, and pressure on the fuel then adjusted responsive to such measurement or analysis.

In one embodiment the present invention provides, in connection with an internal combustion engine with a carburetor system, the improved method of operation to make corrective variations in air to fuel ratios and maintain a substantially constant exhaust gas composition, which comprises, providing a pressure source in communication with the fuel float. chamber of the engine carburetor, and adjusting the pressure level on the fuel therein to increase fuel flow therefrom responsive to a change for at least one variable selected from the following: (1) a decreasing carbon monoxide content in exhaust gases from the engine; (2) an increasing oxygen content in exhaust gases from the engine; (3) a decreasing air temperature; (4) an increasing humidity; (5) a combination of at least one of the variables of (1) through (4) with an increasing barometric pressure and, conversely, decreasing fuel flow responsive to any one or more of the reverse of such listed variables.

In another embodiment, the present invention provides a carburetor control system :for an internal combustion engine which will effect corrective variations in the air to fuel ratio so as to maintain a desired exhaust gas composition, which comprises in combination, a

, gas pressure source connecting through passageway means to the float chamber of the engine. carburetor, an adjustablevalving means in said passageway means to regulate pressure to said chamber, interconnecting at least one sensor means into said system and to transmitter means for producing at least one scaled signal responsive to a change noted by the sensor from an ambient condition or a change in quantity of an engine exhaust gas component, connecting each such transmitter means to a relay to provide a resulting output signal, and connecting said output signal of said relay to said valving means, whereby such output signal effects an adjustment in the air to fuel ratio to said engine.

As hereinbefore set forth, the change in pressure in the carburetor bowl or chamber to provide a change in air to fuel ratio may be made responsive to analyzing means for sensing a change in oxygen or other critical components in exhaust gas stream, as well as by sensing changes in one or all of the various ambient conditions that can effect oxygen content reaching the carburetor mixing zone. A preferred system which will correct for all of the various changes in ambient conditions will thus have a plurality of sensing devices and transmitting means to in turn carry the signals to an addition means or to a computing means such that there may be a single resultant signal to the control instrument varying the pressure to the carburetor bowl. Various types of sensors and transmitting means, as well as totalizing or relay means, may be embodied in a particular overall control system and it is not intended to limit the present invention to any one type of sensortransmitter or to any one type of control which provides a summation or resulting output signal which in turn is connected to the valving means to effect the adjustment in air to fuel ratio.

The sensing or analyzing means may provide a signal for accompanying amplifying and/or transmitter means which provides an electrical or electronic output, or alternatively, the sensing-transmitter means may be hydraulic, pneumatic or mechanical in nature and each output signal carried to a suitable and compatible control means for regulating pressure. In any event, it is within the scope of the present invention to have a system which embodies more .than one sensor-transmitter means to in turn carry signals to a totalizing means, summation means, or other type computing device which will provide a resultant output signal responsive to the various scaled input signals and then transmit a resulting output signal to a control means. Where pneumatic signals are utilized, there are available on the market standard forms of totalizing or computing relay devices which can handle at least up to about six different scaled pneumatic signals and provide a resulting output control signal. Similarly, there are totalizing or computer relay means that can receive electrical or electronic signals and in turn transmit a single resultant electrical or pneumatic output signal capable of regulating either a motor driven or a pneumatically operated control valve means. All of these types of equipment are familiar to those familiar with the use and selection of instrumentation devices and they need not be set forth or described in detail herein.

Reference to the accompanying drawings and the following descriptions thereof serve to further illustrate and describe the present invention, as well as set forth variations as to arrangement and scope.

Additional advantageous features with respect to exhaust gas conversion will also be set forth in connection with the descriptions of the drawings.

FIG. 1 of the drawing indicates diagrammatically one simplified embodiment of the present invention by having a sensor and connecting control device to provide regulation of manifold pressure in turn connective with the carburetor float chamber, whereby the air to fuel ratio may be varied for the engine.

FIG. 2 of the drawing is a graph showing diagrammatically how carburetion or air to fuel ratio has an effect on conversion of the various noxious components in the exhaust gas stream from an internal combustion engine.

FIG. 3 of the drawing indicates diagrammatically the integration of a plurality of sensing means or analyzing means with a computing relay so as to provide regulation of pressure on the carburetor float chamber.

FIG. 4 of the drawing illustrates an alternate modification wherein the pressure line may be a vacuum line connected to the engine manifold.

Referring particularly to FIG. 1 of the drawing, there is indicated an internal combustion engine I with intake manifold means 2 and a superposed carburetor 3 with a float chamber 4 which receives fuel by way of gas inlet line 5. Air for admixture with the gasoline is drawn to the carburetor through air filter means 6 so as to flow downwardly through the throttle area 7 into a venturi section 8 which in turn receives fuel by way of suitable jets or openings, not shown, which are connective with the float chamber 4. Other details of the carburetor system may be conventional and are not indicated in the present diagrammatic drawing. For example, there may be one or more idling jets, acceleration or high speed jets, etc., as well as internal vent means leading from the upper portion of the carburetor float chamber 4 into the air intake section of the carburetor. In any event, whether the carburetor float bowl is vented internally or externally, there is only an effect from atmospheric pressure with respect to the fuel level in the carburetor bowl or float chamber and the application of a varying regulated pressure to such chamber from an outside source will have an effect of increasing or decreasing fuel flow from the chamber through the internal jets of the carburetor into its venturi zone for admixture with incoming air. The quantity of air entering such zone is, of course, responsive to the position of the carburetor throttle as determined by the drivers foot pedal or other linkage means.

In accordance with one embodiment of the present invention, FIG. 1 also shows tubing or other piping means 9 and 10 connecting the intake manifold 2 to control device 12 and to line 11 whereby a varying vacuum can be exerted on the top of the fuel in float chamber 4. A sensor-transmitter is also shown connecting by way ofline 13 to the control device 12. Thus, by the method shown, one or more sensing devices can be used to note a change in oxygen content of the ambient air. As hereinbefore noted, temperature, or a barometric pressure change, or a humidity change, can require a corrective variation in the fuel addition to in turn maintain a desired air to fuel ratio reaching the engine. For example, where the air temperature surrounding the air intake to the engine is increased, there isa resulting decrease in the amount of oxygen per cubic foot of air so that where it is desired to have a substantially constant air to fuel ratio in the operation of the engine, it is necessary to reduce the fuel input in a proportional amount to the reduced oxygen content of the air. With respect to regulation, the control device 12 will be operated to permit a greater vacuum to reach the float chamber 4 and in turn reduce the fuel flow from such chamber into the carburetor mixing zone.

In another example, where the humidity of the ambient air may decrease from that of a previous condition, or from a normal condition, such that the ambient air has a greater amount of oxygen per cubic foot, there may be a sensing of the humidity change and regulation to a suitable control device 12 whereby vacuum on the fuel in the chamber 4 will be lessened and an increased quantity of fuel permitted to flow into the mixing zone of the carburetor. In a similar manner, a sensor-transmitter means may be utilized in combination with the system to note variations in atmospheric pressure and the control device 12 in each instance is regulated responsive to the particular barometric pressure change such that fuel input is modified to provide a change in air to fuel ratio.

There is also indicated diagrammatically, in connection with FIG. 1 of the drawing, two different exhaust gas manifolds 14 connective with exhaust gas converters 15 which would provide for catalytic conversion of a hot exhaust gas stream leaving engine 1. In other words, in accordance with the object of the present invention, it is desired to provide for minor variations in air to fuel ratio over that which would be normally provided from conventional carburetor adjustments whereby any one or all of the varying ambient conditions can effect a pressure change and a resultant modification in the fuel input. This, in turn, will provide a better operation of the catalyst in the exhaust gas converters 15. As is hereinbefore noted, it is to be realized that control means 12 can also be operated responsive to a sensor or analyzer means which is directly connective within the converter means 15 so as to read variations in oxygen or CO content, whereby a more stabilized or preferable air to fuel ratio can be provided at the carburetor zone from pressure on the fuel in the carburetor bowl. For example, there are various types of oxygen sensing devices which can provide an electronic or pneumatic signal which may be directly connective with the control means 12, and in view of their commercial availability it is not believed necessary to provide details of such types of apparatus herein. Reference may be made to Handbook of Automation Computation and Control Volume 3, Published by John Wiley & Sons, Inc., Chapter 24, pages 29-34; or to Perry s Chemical Engineers Handbook, Fourth Edition, Section 22, pages 31 32.

With reference to the graph shown in FIG. 2, there is shown diagrammatically the conversion of nitrogen oxides (NO), hydrocarbons (HC) and carbon monoxide (CO) with respect to the percent of CO present in the exhaust gas stream which in turn is a measure of the carburetion or air to fuel ratio. In other words, the percent CO present will be high where there is a low air to fuel ratio and conversely, lower where there is more oxygen present as a result of a higher air to fuel ratio.

With particular reference to the chart of FIG. 2, there is indicated an air to fuel ratio of 14.50 at a point corresponding with the 0.9 percent of CO, a 14.35 air to fuel ratio along the ordinate corresponding to 1.2 CO and intermediate ratios at the 1.0 and 1.1 CO marks. It is to be further noted that within the zone of 14.50 to 14.40 there are 73 percent or better HC and NO conversions while CO conversion is above 90 percent. Conversely, when the air to fuel ratios are greater or less than the range indicated, there will be a poor conversion of the NO or the hydrocarbons. In any event, the graph clearly shows that for a catalytic converter utilizing an optimum type of catalyst to effect the conversion of the noxious components in the exhaust gas stream there is the necessity to control the percent of CO, or oxygen, as determined by the air to fuel ratio for the engine operation, whereby there is a conversion condition generally optimum for each of the undesirable components and their substantial elimination from the exhaust gas stream.

Specifically, it may be set forth that the data for the curves shown in FIG. 2 were derived from the operation of an 8 cylinder engine in a 1970 Oldsmobile which in turn was being operated under test conditions with 7 mode cycles. This 7 mode operating cycle was as follows:

MODE TIME, SEC. Idle, 2O Accelerate to 30 mph., 14 Cruise at 30 mph., 15 Decelerate to 15 mph., 11 Cruise at 15 mph., 15 Accelerate to 50 mph., 29 Decelerate to idle. 33

Samples of the exhaust gases were analyzed in infrared analysis. Also, it is to be noted that the percent CO and the air to fuel ratios indicated along the horizontal ordinate will vary in accordance with the particular mode of operation and that the figures shown are weighted in order to provide an averaged value applying to the total 7 mode operating cycle.

In FIG. 3 of the drawing, there is indicated diagrammatically a carburetor control system which has a carburetor float bowl section 16 provided with pressure regulation means from piping or tubing 17 having control valve 18. The pressure line 17 may be a portion of a vacuum line 19 connective with the engine manifold 20 (See FIG. 4) or alternatively, it may comprise an extended portion of line 21, with valve 22, from an air storage tank 23. The latter may be a small tank suitable to hold relatively low pressure air from a small compressor means 24 so as to have an air supply line 25 connective with computing relay 26. A controlled pneumatic output is thus provided from the latter through line 27 to control valve means 18.

A plurality of sensor-transmitter means are indicated diagrammatically at 28, 29, 30, 31 and 32 for respectively providing: oxygen analysis; 0 signal transmitter means; temperature change signals; barometric pressure change signals; and humidity variation signals. In combination with the latter, there is also indicated diagrammatically the use of air pressure lines 33, 34, 35 and 36 to provide a pneumatic form of transmission means to the plurality of sensor-transmitter means shown as 29, 30, 31 and 32. Still further, there are indicated lines 37, 38, 39 and 40 to effect the transmission of the varying pneumatic signals from the respective transmitter means to the computer relay means 26. The latter may comprise a standard pneumatic form of totalizing relay adapted to handle a plurality of pneumatic signals and in turn transmit a resultant output signal by way of line 27 to control valve means 18. Totalizing or computing relays to meet this type of service are readily available from instrument suppliers and are well known to those skilled in the instrument arts. Reference may again be made to the heretofore noted Handbook of Automation Computation and Control," Chapter 7, pages 60 et seq., with regard to computing relays. The same chapter, at pages 17 18, sets forth converting electrical and electronic signals to pneumatic control or transmission, all of which might be utilizedin connection with certain of the transmitter sealers indicated at 29, 30, 31 and 32. Temperature signals can be electrical from a thermocouple or mechanical from coiled bimetal strips, etc., which can readily adjust electrical or pneumatic flow control means. Also, barometric pressure readings and humidity readings can be taken from coiled members to give mechanical motion and again electrical or pneumatic transmission from transmitter-scaler means. Reference may still further be made to Perrys Handbook, Table 22-16 for humidity reading and control; pages 22-6 to 22-12 for temperature measurements, and pages 22-13 to 22-17 for pressure measurements and signal transmission means.

By way of further illustration, the analyzer-transmitter means at 28 and 29 of FIG. 3 of the drawing may embody the O analyzer of page 29, Chapter 24 of the Handbook of Automation, Computation and Control coupled with electrical resistance signal converting means, such as described on pages 17 and 18 of Chapter 7 of the same book, whereby the pneumatic pressure of line 33 is scaled in line 37 to computing relay 26. The temperature transmitter-sealer at 30 could embody a thermocouple of resistance thermometer coupled to a electropneumatic converter means as heretofore noted in connection with 29. Alternatively, the temperature sensing device could be a Bourdon tube or bi-metal strip which gives a displacement action to control flow in line 38 to computing relay 26. Various temperature sensing means are well known such as heretofore noted as being described in Perrys Chemical Engineers Handbook," pages 22-6 to 22-12 or also in the Handbook of Automation, Computation and Control, Chapter 20, pages 24-25. The barometric pressure transmitter-scaler at 31, as well as the humidity transmitter-sealer at 32, could be sensors such as shown respectively in the aforesaid Handbook of Automation at pages 20-12 through 20-6 and Perry s Handbook pages 22-37 and 22-38, whereby a displacement action could in turn regulate flow in the respective lines 39 and 40 to relay 26. The latter may be a Moore Nullmatic M/F, such as shown in the Handbook page 7-60, or other equivalent type. In any event, as noted hereinbefore, it is not intended to limit the scope of the present invention to a specific type of instrumentation in that equivalent instrumentation means may be provided through the use of electrical or electronic signals which will carry to a computer relay and a resultant or totalized output signal which is either pneumatic or electric may be used to regulate the pressure control means 18 in line 17.

As specific alternative means, thevarious sensor or analyzer means may be connected to electrical or electronically sensitive transmitting means such that scaled or weighted signals may be simultaneously supplied to a computer or totalizing relay means adapted to effect the summation of suchtype signals and in turn provide a single output signal. Actually, the signals may be in a digital or analog form and the various signals in turn carried to a computing type relay so as to provide that the net effect of the various sensing means can be used to control pressure on the fuel and regulate air to fuel ratios. Typically, each transmitter means will incorporate, or have in combination therewith, suitable weighted or scaled adjustment means whereby the net effect of each type of reading or analysis can be sent to the computing relay for subsequent transmission of a net signal to the actual regulating means.

The pressure adjustment which is to be made on the carburetor float chamber 16, may be a vacuum change resulting from the connection of lines 17 and 19 to the engine manifold or, alternatively, as shown in the full lines of FIG. 3, there may be the regulation of an actual low superatmospheric pressure change carrying through lines 21 and 17 from the small pressure tank 23. Inasmuch as a small compressor and storage tank may readily be provided under the hood of an automobile and in convenient combination with the engine, it seems appropriate that the pressure regulation change on the carburetor float chamber be from regulated low pressure air and that the computing relay as well as the sensor-transmitter means connective therewith be operated pneumatically from the same air system. The pneumatic operation also seems of advantage since such types of instrumentation and relays are presently available in small compact forms or could be readily produced in a manner to minimize space requirements. A variation in one or more of the various sensor-transmitter means, as a result of a change in an ambient condition, can be corrected in a manner similar to that described in connection with FIG. 1 of the drawing, and it is not believed necessary to again describe in detail the various resulting changes in the air to fuel ratios from one or more changes in conditions. In other words, where any one condition is such as to decrease oxygen content in the air stream passing to the carburetor system through the air filter means, there can be a correcting variation in fuel input by a correcting decrease in pressure on the fuel in the carburetor float chamber to in turn provide adecrease of fuel input into the mixing zone of the carburetor.

In any event, it will be seen that the present improved method and means provide a novel and relatively simple approach providing corrective variations in carburetion for an internal combustion engine and in turn provide a means for stabilizing the oxygen and CO components within the exhaust gas stream so as to permit optimum conversion in a catalytic converter system.

I claim as my invention:

1. In the operation of an internal combustion engine with a carburetor system, the improved method of operation to make corrective variations in air to fuel ratios and maintain a desired exhaust gas composition, which comprises, providing a pressure source other than atmospheric and remote from the carburetor in communication with the fuel float chamber of the engine carburetor, and adjusting the pressure level on the fuel therein to change fuel flow therefrom responsive to the 0 content in the air stream to the carburetor.

2. The method of claim 1 further characterized in that the pressure source in communication with the fuel float chamber is the vacuum provided by the intake manifold of said engine.

3. The method of claim 1 further characterized in that the pressure source in communication with the fuel float chamber comprises a separate low pressure pneumatic supply.

4. A carburetor control system for an internal combustion engine providing corrective variations in the air to fuel ration so as to maintain -a desired exhaust gas composition, which comprises in combination, a gas pressure source other than atmospheric and remote from the carburetor connecting through passageway means to the float chamber of the engine carburetor, an adjustable valving means in said passageway means to regulate pressure to said chamber, a sensor means interconnected into said system, a transmitter means, said transmitter means producing at least one scaled signal responsive to a change noted by the sensor in oxygen content change reaching said carburetor, said transmitter means having a computing relay in interconnection to therewith provide a resulting output signal, and the output signal of said relay being interconnected with said valving means, whereby such output signal effects an adjustment in the air to fuel ratio to said engine.

5. A carburetor control system to effect corrective variations in the air to fuel ratio for an internal combustion system so as to maintain a desired exhaust gas composition, which comprises in combination, an air pressure source other than atmospheric and remote from the carburetor connecting through conduit means to the float chamber of the engine carburetor, an adjustable valve means in said conduit means, a multifunction computing relay providing an averaged transmitted power source connecting to said adjustable valve means, and at least two signal connections to said computing relay sensed from atmospheric condition and from an exhaust gas component, each of which shows a change in oxygen content to the carburetor; whereby the effect of at least two signals will be averaged and provide a resulting adjustment in fluid pressure on said float chamber from said valve means.

6. The carburetor control system of claim further characterized in that said computing relay provides a resultant pneumatic output signal connective with said adjustable valve means and said signal connections to said computer relay from said transmitter means are scaled pneumatic signals, whereby said computing relay effects the totalizing of a plurality of pneumatic signals being transmitted thereto.

7. The carburetor control system of claim 5 further characterized in that said computing relay providing an averaged signal output connecting to said adjustable valve means receives a plurality of weighted electrical signals from each of the plurality of transmitter means, and said computing relay effects the totalizing of such electrical signals to provide a resultant averaged output signal.

8. The carburetor control system of claim 7 still further characterized in that said power source connecting to said computing relay is electrical whereby there is electrical power regulation of said adjustable valve means.

9. The carburetor control system of claim 7 still further characterized in that said power source connecting with said computer relay is pneumatic, whereby an averaged pneumatic output signal is transmitted to a pneumatically operated adjustable valve means for regulation of pressure on the float chamber of the engine carburetor.

10. The method of claim 1 further characterized in that there is provided an increase in pressure level to increase fuel flow responsive to a decreasing CO content in the exhaust gases from the engine and, conversely, decreasing pressure level responsive to an increasing CO content in the exhaust.

11. The method of claim 1 further characterized in that there is provided an increase in pressure level to increase fuel flow responsive to an increasing 0 content in the exhaust gases from the engine and, conversely, decreasing pressure level responsive to a decreasing 0 content in the exhaust.

12. The method of claim 1 further characterized in that there is provided an increase in pressure level to increase fuel flow responsive to a decreasing air temperature and, conversely, decreasing pressure level responsive to an increasing air temperature.

13. The method of claim 1 further characterized in that there is provided an increase in pressure level to increase fuel flow responsive to an increasing humidity of ambient air and, conversely, a decrease in pressure level for a decreasing humidity. 

1. In the operation of an internal combustion engine with a carburetor system, the improved method of operation to make corrective variations in air to fuel ratios and maintain a desired exhaust gas composition, which comprises, providing a pressure source other than atmospheric and remote from the carburetor in communication with the fuel float chamber of the engine carburetor, and adjusting the pressure level on the fuel therein to change fuel flow therefrom responsive to the O2 content in the air stream to the carburetor.
 2. The method of claim 1 further characterized in that the pressure source in communication with the fuel float chamber is the vacuum provided by the intake manifold of said engine.
 3. The method of claim 1 further characterized in that the pressure source in communication with the fuel float chamber comprises a separate low pressure pneumatic supply.
 4. A carburetor control system for an internal combustion engine providing corrective variations in the air to fuel ration so as to maintain a desired exhaust gas composition, which comprises in combination, a gas pressure source other than atmospheric and remote from the carburetor connecting through passageway means to the float chamber of the engine carburetor, an adjustable valving means in said passageway means to regulate pressure to said chamber, a sensor means interconnected into said system, a transmitter means, said transmitter means producing at least one scaled signal responsive to a change noted by the sensor in oxygen content change reaching said carburetor, said transmitter means having a computing relay in interconnection to therewith provide a resulting output signal, and the output signal of said relay being interconnected with said valving means, whereby such output signal effects an adjustment in the air to fuel ratio to said engine.
 5. A carburetor control system to effect corrective variations in the air to fuel ratio for an internal combustion system so as to maintain a desired exhaust gas composition, which comprises in combination, an air pressure source other than atmospheric and remote from the carburetor connecting through conduit means to the float chamber of the engine carburetor, an adjustable valve means in said conduit means, a multi-function computing relay providing an averaged transmitted power source connecting to said adjustable valve means, and at least two signal connections to said computing relay sensed from atmospheric condition and from an exhaust gas component, each of which shows a change in oxygen content to the carburetor; whereby the effect of at least two signals will be averaged and provide a resulting adjustment in fluid pressure on said float chamber from said valve means.
 6. The carburetor control system of claim 5 further characterized in that said computing relay provides a resultant pneumatic output signal connective with said adjustable valve means and said signal connections to said computer relay from said transmitter means are scaled pneumatic signals, whereby said computing relay effects the totalizing of a plurality of pneumatic signals being transmitted thereto.
 7. The carburetor control system of claim 5 further characterized in that said computing relay providing an averaged signal output connecting to said adjustable valve means receives a plurality of weighted electrical signals from each of the plurality of transmitter means, and said computing relay effects the totalizing of such electrical signals to provide a resultant averaged output signal.
 8. The carburetor control system of claim 7 still further characterized in that said power source connecting to said computing relay is electrical whereby there is electrical power regulation of said adjustable valve means.
 9. The carburetor control system of claim 7 still further characterized in that said power source connecting with said computer relay is pneumatic, whereby an averaged pneumatic output signal is transmitted to a pneumatically operated adjustable valve means for regulation of pressure on the float chamber of the engine carburetor.
 10. The method of claim 1 further characterized in that there is provided an increase in pressure level to increase fuel flow responsive to a decreasing CO content in the exhaust gases from the engine and, conversely, decreasing pressure level responsive to an increasing CO content in the exhaust.
 11. The method of claim 1 further characterized in that there is provided an increase in prEssure level to increase fuel flow responsive to an increasing O2 content in the exhaust gases from the engine and, conversely, decreasing pressure level responsive to a decreasing O2 content in the exhaust.
 12. The method of claim 1 further characterized in that there is provided an increase in pressure level to increase fuel flow responsive to a decreasing air temperature and, conversely, decreasing pressure level responsive to an increasing air temperature.
 13. The method of claim 1 further characterized in that there is provided an increase in pressure level to increase fuel flow responsive to an increasing humidity of ambient air and, conversely, a decrease in pressure level for a decreasing humidity. 